The relationship between increased seryl-tRNA levels and the induction of phosvitin synthesis by estrogen will be further investigated. The absolute change in amount of individual tRNA species will be determined and these amounts on free and membrane-bound polysomes will be compared. The hormonal, tissue and species specificity of the seryl-tRNA changes will be examined to determine whether the changes in levels can be dissociated from the induction of phosvitin synthesis. The specific hepatic tRNA for phosphoserine will be purified by interaction with elongation factor, Tu and its possible function will be evaluated by comparing its presence on soluble and polysomal tRNA.